|As far as I know, you can't bold only a portion of a Text string that is the result of a formula. I know of 3 ways to accomplish your goal:|
1 - Carefully size and position multiple cells to make it look like one and then Bold the cell that contains the portion that you want bolded.
2 - Use VBA (a macro) to convert the result of the formula into a value and bold the desired characters via the same code. Let me know if that method interests you.
3 - Carefully size and position a text box that is linked to a cell which contains the portion that you want bolded as described here:
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